Molten Salt keeps solar energy plants running at night. [+Christmas quadrotors]

In July, Italy opened the world’s first Concentrated Solar Power (CSP) plant of its kind.

Picture of a CSP plant

This CSP plant's been featured in a few movies; you may recognize it.

First, a little bit about what they are. CSP plants have a simple concept behind them: since electricity is almost always generated through mechanical movement (wind turbines, hydroelectric dams—even coal and nuclear plants use their fuels to drive turbines), CSPs collect the heat generated by sunlight to eventually produce steam, which in turn drives turbines. This is different from photovoltaic power plants, which are the ones most people consider solar power.

Most CSP plants around today use synthetic oils to collect the sunlight, because liquids have a more efficient heat-transfer rate. The oils are then used to boil the water which drives the turbines. But this CSP plant in Italy has a different medium.

Salt. To be precise, sodium/potassium nitrate rather than sodium chloride—table salt—but still. Salt.

Why, though? Easy: molten salt retains heat like a boss. That means it can be heated during the day to over 1000 degrees Fahrenheit—that is then used to boil the water and drive the turbines—but also that the salt will remain hot long after sunset. Suddenly solar power plants can produce energy at night, when there is no sun to be seen. This kind of improvement drastically improves the efficiency of such things, which would ordinarily be limited to running only while the sun is up.

Older CSP plants had a tank of molten salt to store heat, but the one just built in Sicily uses it to collect the heat.

It looks like California is following suit with one of its own, too. Awesome.

These CSP plants can produce as much as 350 Megawatts (350 x 106 watts), which is enough to power many tens of thousands of homes. But solar energy only has room to grow: “Based on the average of 1.366 kW/m2 of total solar irradiance the total energy flow of sunlight striking Earth’s atmosphere is estimated at 174 Petawatts [174 x 1015 watts]” (Wikipedia). If we could harness that, the human race would pretty much be set forever.

On an irrelevant note, but related to these posts [this one and this one], watch this:

Enjoy your holidays, no matter what you celebrate! Or, at the very least, enjoy a well-earned break from school.


6 thoughts on “Molten Salt keeps solar energy plants running at night. [+Christmas quadrotors]

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